import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String str = in.nextLine();
        String tmp = "";
        String s = "";
        int count = 0;
        for (int i = 0; i < str.length(); i++) {
            while (i < str.length() && str.charAt(i) >= '0' && str.charAt(i) <= '9' ) {
                tmp += str.charAt(i);
                i++;
            }
            if (tmp.length() > count) {
                count = tmp.length();
                s = tmp;
            }
            tmp = "";
        }
        System.out.println(s);
    }
}